Tumor necrosis factor alpha (TNF-α) is a cytokine that has been implicated in mediating shock and the pathophysiology of a variety of human diseases and disorders including sepsis, infections, autoimmune diseases eg. rheumatoid arthritis, Crohn's disease, ulcerative colitis and other bowel conditions, psoriasis, toxic shock, transplant rejection and graft-versus-host disease. TNF-α is produced primarily by activated macrophages and T lymphocytes, but also by neutrophils, endothelial cells, keratinocytes and fibroblasts during acute inflammatory reactions.
Because of its role in inflammation, TNF-α has emerged as an important target for inhibition in efforts to reduce the symptoms of inflammatory disorders. Various approaches to inhibition of TNF-α for the clinical treatment of disease have been pursued, including particularly the use of soluble TNF-α receptors and antibodies specific for TNF-α.
Domain Antibodies
Domain antibodies (dAb) are the smallest functioning binding units of antibodies and correspond to the variable regions of either the heavy (VH) or light (VL) chains of antibodies. Domain antibodies have a molecular weight of approximately 13 kDa, or less than one tenth the size of a full antibody.
In contrast to conventional antibodies, domain antibodies are well expressed in bacterial, yeast and mammalian systems. Their small size allows for higher molar quantities per gram of product, thus providing a significant increase in potency per milligram dose. In addition, dAbs can be used as building blocks to create therapeutic products such as multiple targeting dAb-containing molecules in which two or more dAbs bind to two or more distinct molecular targets, or dAbs may be incorporated into structures designed for pulmonary or oral administration.
The present inventors have now devised a novel domain antibody construct comprising an immunoglobulin variable domain linked to a constant region including a truncated CH1 domain. It is postulated that the inclusion of a constant region will assist in prolonging the in vivo half-life of the dAb which is typically of a short duration.
New World Primate Immunoglobulin
Evolutionarily distant primates, such as New World primates are sufficiently similar to human to have antibodies similar to human antibodies so that the host does not generate an anti-antibody immune response when such primate-derived antibodies are introduced into a human. New World primates (infraorder-Platyrrhini) comprise at least 53 species commonly divided into two families, the Callithricidae and Cebidae. The Callithricidae consist of marmosets and tamarins. The Cebidae includes the squirrel monkey, titi monkey, spider monkey, woolly monkey, capuchin, night or owl monkey and the howler monkey.
Previous studies have characterised the expressed immunoglobulin heavy chain repertoire of the Callithrix jacchus marmoset (von Budingen H-C et al., Characterization of the expressed immunoglobulin IGHV repertoire in the New World marmoset Callithrix jacchus. Immunogenetics; 53:557-563 (2001)). Six IGHV subgroups were identified which showed a high degree of sequence similarity to their human IGHV counterparts. The framework regions were more conserved when compared to the complementarity determining regions (CDRs), with the greatest degree of variability located in CDR3. The degree of similarity between C. jacchus and human IGHV sequences was less than between Old World monkeys and humans.